Small duct primary sclerosing cholangitis without inflammatory bowel disease is genetically different from large duct disease

Small duct primary sclerosing cholangitis (PSC) is phenotypically a mild version of large duct PSC, but it is unknown whether these phenotypes share aetiology. We aimed to characterize their relationship by investigating genetic associations in the human leucocyte antigen (HLA) complex, which represent the strongest genetic risk factors in large duct PSC.Four classical HLA loci (HLA-A, HLA-B, HLA-C and HLA-DRB1) were genotyped in 87 small duct...